volatile

adjective

• 1(of a substance) easily evaporated at normal temperatures: volatile solvents such as petroleum ether, hexane, and benzene

• 2liable to change rapidly and unpredictably, especially for the worse:the political situation was becoming more volatile
• (of a person) liable to display rapid changes of emotion: a passionate, volatile young man

• 3(of a computer’s memory) retaining data only as long as there is a power supply connected.

noun

• a volatile substance.